Added wrappers for calibration functions.  Fixed memory leak in default_calibration_path() method.
Added wrappers for calibration functions.  Fixed memory leak in
default_calibration_path() method.

olsonse/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,olsonse/comedilib,olsonse/comedilib,olsonse/comedilib,olsonse/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib,Linux-Comedi/comedilib